In the field of optical imaging, there are many types and configurations of charge coupled device (CCD) arrays. CCD arrays are composed of many light, or photon, sensing cells. Photons striking these cells cause the cells to produce an electrical charge. The charge from these cells is sequentially communicated to an analog shift register, often called a horizontal shift register or a CCD shift register.
The CCD shift register receives the charge from each cell sequentially, the image usually being read out from the left to right then top to bottom. The charge from each of the cells is stored in a register position and then output sequentially from the register to a CCD output node.
The CCD output node holds the charge, creating a voltage differential. The voltage differential is viewed at intervals and communicated to an analog to digital converter, usually through some combination of buffers and amplifiers. The analog to digital converter digitizes the voltage to produce pixels that form an image.
One variation to this configuration is to include more than one output CCD shift register. The output CCD shift registers may be physically contiguous, or not. The multiple physically contiguous output CCD shift registers function as multiple output CCD shift registers, not a single output CCD shift register. The output CCD shift registers output charges to a like number of CCD output nodes, each output CCD shift register outputting its charge to only one CCD output node.